Container base



FIG. 1 is a top, front perspective view of a container base showing my new design;

FIG. 2 is a bottom, rear perspective view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a front elevational view thereof;

FIG. 6 is a rear elevational view thereof;

FIG. 7 is a left side elevational view thereof; and,

FIG. 8 is a right side elevational view thereof.

The broken lines shown in the drawings represent portions of the container base and form no part of the claimed design. 

CLAIM The ornamental design for a container base, as shown and described. 